THE G-PROTEIN G(13) MEDIATES INHIBITION OF VOLTAGE-DEPENDENT CALCIUM CURRENT BY BRADYKININ

In neuroblastoma-glioma hybrid cells, bradykinin has dual modulatory effects on ion channels: it activates a K+ current as well as inhibits the voltage-dependent Ca2+ current (I-Ca,I-V). Both of these actions are mediated by pertussis toxin-insensitive G proteins. Antibodies raised against the homologous G(q) and G(11) proteins suppress only the activation of the K+ current; this suggested that at least two distinct G protein pathways transduce diverse effects of this transmitter. Here, we show that the inhibition of I-Ca,I-V by bradykinin is suppressed selectively by intracellular application of antibodies specific for G(13). This novel G protein may play a general role in the inhibition of I-Ca,I-V by pathways resistant to pertussis toxin.